The present invention relates to a carrying apparatus provided in an electrophotographic copier, for example, for holding and carrying paper, and an image forming apparatus for forming an image on the paper carried by the carrying apparatus.
An apparatus shown in FIG. 8, for example, is well known as an image forming apparatus of this type.
In FIG. 8, reference numeral 101 denotes the main unit of the apparatus. The main unit 101 contains an image forming unit 102 for forming an image on the paper as a carried medium and a paper feed unit 103 for feeding paper to the image forming unit 102.
The image forming unit 102 is provided with a photoconductive rotary drum 106 as an image holding member. On the circumference of the photoconductive drum 106, an electrifier 107, scanning optics to take in an image light 108 (not shown), a developing unit 109, a transfer charger 110, a separation charger 111, a cleaning unit 112, and a de-electrifier 113 are arranged along the drum rotating direction.
The paper feed unit 103 has a paper feed cassette 115 set at the inner bottom of the main unit 101, and a paper carrying path 116 which carries upward the paper fed from the paper feed cassette 115. Paper P is loaded in the paper feed cassette 115, and fed by rotation of a paper feed roller 114. In the paper feeding direction of the paper feed roller 114, a separation roller 124 and a feed roller 125 are provided to separate and feed sheets of paper one by one.
The paper carrying path 116 is provided along a vertical direction. In the carrying path 116, a pair of carrying rollers 117, a pair of registration rollers 118, an image transfer unit 119, a pair of fixing rollers 120 and a pair of eject rollers 121 are arranged in order from downstream to upstream. The pair of carrying rollers 117 comprises a drive roller 117a as a first roller and a follower roller 117b as a second roller which rotates contacting with the drive roller 117a. An ejected paper tray 122 is provided on the paper ejection side of the pair of eject rollers 121.
When an image is formed, the surface of the photoconductive drum 106 is electrified by the electrifier 107, the image light 108 is radiated to the surface of the electrified photoconductive drum 106, and an electrostatic latent image corresponding to a document image is formed. This electrostatic latent image sent to the developing unit 109 by the rotation of the photoconductive drum 106, and the latent image is developed to a toner image by the developer supplied from the developing unit 109.
On the other hand, in this time, the paper P is supplied by rotation of the paper feed roller 114, and the paper P is held and carried by the pair of carrying rollers 117. The paper P is adjusted in position by the pair of registration rollers 118, sent to the image transfer unit 119 located between the photoconductive drum 106 and transfer charger 110, where the magnetic toner image formed on the photoconductive drum 106 is transferred to the paper P. The paper P having the transferred magnetic toner image is separated from the photoconductive drum 106 by the action of the separation charger 111, and carried. The paper P is sent to the pair of fixing rollers 120, where the transferred toner image is fixed to the paper P, and the paper is ejected to the ejected paper tray 122 by the rotation of the pair of paper eject rollers 121.
The paper supplied from the paper feed cassette 115 and sent to the carrying path 116 may jam in the pair of carrying rollers 117. To enable removal of the jammed paper, an open/close cover 127 which opens and closes the carrying path 116 is provided in the lower part of one side of the main unit 101. The drive roller 117a of the pair of carrying rollers 117 is fixed to the main unit 101, and the follower roller 117b is fixed to the open/close cover 127. The follower roller 117b contacts with and separates from the drive roller 117a each time the open/close cover 127 is closed and opened.
The lower side of the open/close cover 127 is rotatably fixed to the main unit 101 through a support shaft 129, and the upper side is provided with a lock device 130 which locks the open/close cover 127 to the main unit 101.
The lock device 130 comprises a lock lever 131 and a stopper pin 132. The lock lever 131 is rotatably fixed to the open/close cover 127 through a support shaft 133. The stopper pin 132 is fixed to the main unit 101. The forward end of the lock lever 131 is formed with a hook 131a, and the rear end is connected to an operation lever 134. The lock lever 131 is rotated by the operation of the operation lever 134, so that the open/close cover 127 is locked to the main unit 101 with the hook 131a removably engaged with the stopper pin 132.
When removing paper jammed in the pairs of carrying rollers 117, the operation lever 134 is operated and the lock lever 131 is turned in the direction of arrow A centering around the support shaft 133. As a result, the hook 131a of the lock lever 131 separates from the stopper pin 132, and the lock is released. After the lock is released, the open/close cover 127 is opened by turning it in the direction of arrow B centering around the support shaft 129. As a result, the follower rollers 117b separates from the drive roller 117a, the carrying path 116 is opened, and the jammed paper can be removed.
If the drive roller 117a and follower roller 117b which constitute the pair of carrying rollers 117 are not exactly positioned, the paper carrying accuracy will be lowered.
Thus, in the conventional apparatus, the dimensional accuracy of the open/close cover 127 to which the follower roller 117b is fixed is strictly controlled, or a mechanism for positioning the drive roller 117a and follower roller 117b is required as an optional unit.
However, there is a problem in the former case that the dimensional control of the open/close cover is difficult, and another problem arises in the latter case that the number of parts increases and the cost increases.
The present invention has been made in order to solve the above problems. It is an object of the present invention is to provide a carrying apparatus capable of positioning a first roller and a second roller without requiring an optional positioning mechanism, and an image forming apparatus.
According to an aspect of the present invention, there is provided a carrying apparatus comprising a main unit which is opened and closed by an open/close cover; a carrying device which has a first roller supported by the main unit through a first support shaft, and a second roller supported by the open/close cover through a second support shaft, and which holds and carries a material to be carried by the first and second rollers; and a lock device which is fixed to the second support shaft and is removably engaged with the first support shaft, for locking the open/close cover to the main unit and determining the relative position of the first and second rollers.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.